Naturally Kiawah Magazine Volume 37 | Page 27

Home gardeners can help protect water resources by installing a rain garden . Rain gardens are designed to mimic the natural water cycle by capturing water that flows off of impervious surfaces and allowing this water to infiltrate the ground . Rain gardens not only manage stormwater runoff but can also assist residents with flooding and erosion issues , add beauty to the home landscape , and provide habitat for pollinators and songbirds .
Rain Garden Design The term “ rain garden ” is really a misnomer as rain gardens are dry more often times than wet . Rain gardens are designed for infiltration , providing a place for stormwater runoff to soak into the soil . Rain gardens are not mosquito breeding grounds . Rain gardens typically drain in under 24 hours , while mosquitoes require seven to 10 days of standing water to lay and hatch eggs .
A percolation ( perc ) test will help determine if a rain garden is appropriate for your yard . Dig a “ perc ” hole six inches deep by six inches wide and fill it with water . Observe and note how many inches have drained each hour . If the water has drained from the hole in under 24 hours , then the soil conditions are good for a rain garden . If it takes more
than 24 hours to drain , then the location is not a good place for a rain garden ; instead , consider a bog garden or backyard wetland .
Rain gardens are typically installed to capture runoff from rooftops , lawns , or driveways . Rain gardens should be placed at least 10 feet from the foundation of the home and at least 25 feet from septic system drain fields . Always call # 811 in South Carolina before digging to avoid hitting buried cables or pipes . Water can be directed toward a rain garden using gutters and downspouts or by placing the rain garden in an area that receives overland flow .
The size of a rain garden depends on three considerations : available space , total area of impervious surface that the rain garden will be capturing , and existing soil type . When performing the perc test in sandy , quick-draining soils , the water will drain in less than six hours . In these conditions , the rain garden should be approximately 20 percent of the impervious area that is directed towards the rain garden ( Note : Likely only a section of your roof drains toward rain garden ). When performing the perc test in slow-draining soils , the water may not drain until closer to 24 hours . In these conditions , the rain garden should be at least 30 – 50 percent of the impervious area .
WINTER / SPRING 2017 • VOLUME 37
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